1. Field of the Invention
The invention relates to a microscope apparatus including a sensor which detects a state of a driver such as a stage.
2. Description of the Related Art
Recent microscope apparatuses frequently used include electronic microscopes of the type that electrically controls various drivers that drive, for example, a revolver used to change an objective lens and a stage used to mount a sample as an observation object.
To control the operation of such a driver, it is necessary to detect the current state of the driver by using a sensor provided as a sensor section such as a photo-interrupter or a Hall integrated circuit (IC).
Microscope apparatuses using sensors for detecting the state of drivers include those of the type described hereunder.
A main body of the microscope apparatus has two sensors, namely, an upper limit sensor and a lower limit sensor, which are disposed at a predetermined spacing along a movement direction of a stage. In addition, the main body has a light shield provided in the stage. Upon movement of the stage, the light shield enters an optical axis of a photo-interrupter and thereby blocks the optical path.
When a user operates an operation switch of the main body of the microscope apparatus to drive the stage upward, the light shield enters the optical axis of the photo-interrupter of the upper limit sensor to thereby block the optical path. Thereby, the upper limit sensor becomes the ON state and detects that the stage has been driven up to the upper limit. Conversely, when the stage is driven downward, the light shield enters the optical axis of the photo-interrupter of the lower limit sensor to thereby block the optical path. Thereby, the lower limit sensor becomes the ON state and detects that the stage has been driven down to the lower limit.
In the configuration described above, power is continually supplied to the upper limit sensor and the lower limit sensor, regardless of the detection of the light shield according to the driving of the stage. Therefore, even when the state where the stage is not driven at all, power continually flows to the upper limit sensor and the lower limit sensor.
To overcome the problem, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2000-184116, a scheme has been proposed in which an oscillatory circuit is used to supply power to sensors at predetermined intervals and thereby to reduce power consumption.